The invention is based on a hand-held power jigsaw with a clamping device for a reciprocating tool, in particular a jigsaw blade.
A known hand-held power jigsaw has a toolless clamping device for a jigsaw blade (DE 602 05 146 T2). This clamping device has a centering piece affixed to the lifting rod, with an axial insertion slot for a shaft of a jigsaw blade as well as a cup-shaped clamping sleeve that is situated concentric to the centering piece and is able to rotate in relation to the centering piece. The cylindrical centering piece contains a radially extending transverse aperture, which is oriented transversely to the insertion slot and opens onto the outer circumference of the centering piece and into the insertion slot. A clamping element is inserted into the transverse aperture and at one end, protrudes from the transverse aperture with a head that is larger than the transverse aperture and at the other end, protrudes into the insertion slot. The part of the clamping element protruding into the insertion slot is provided with an insertion bevel so that the jigsaw blade shaft inserted into the insertion slot from beneath can slide the clamping element outward, transversely in relation to the insertion slot. To slide the clamping element in the opposite direction, the clamping sleeve has a clamping curve, which extends over a rotation angle range of the clamping sleeve and whose radius decreases continuously over the rotation angle range. The clamping curve rests against the head of the clamping element and as the clamping sleeve is rotated, slides the clamping element deeper and deeper into the insertion slot. One end of a prestressed torsion spring engages an intermediate piece and its other end engages the clamping sleeve; the torsion spring strives to rotate the clamping sleeve in a direction such that the clamping curve slides the clamping element into the insertion slot to its maximum depth.
In order to insert the jigsaw blade, the clamping sleeve is rotated by means of a manually rotatable collar counter to the restoring force of the torsion spring so that the clamping curve lifts away from the head of the clamping element and as the jigsaw blade is inserted, it is able to move the clamping element out of the insertion slot in a radially outward direction by means of the insertion bevel. The clamping element is slid a greater or lesser distance outward, depending on the thickness of the saw blade. If the collar is released again, then the reverse rotation of the clamping sleeve produced by the restoring force of the torsion spring causes the clamping curve to slide along the head of the clamping element and press the clamping element against the shaft of the jigsaw blade, which for its part, rests against the wall of the centering piece opposite from the clamping element in the insertion slot. At the end of the reverse rotation of the clamping sleeve produced by the torsion spring, the saw blade is clamped in a frictionally engaging fashion between the centering piece and the clamping element.
In the bottom of the cup-shaped clamping sleeve, a slot is provided, whose length is greater than the width of a transverse piece protruding from the shaft of the jigsaw blade so that the transverse piece can be slid through the slot in the bottom. In the release position of the clamping device, which is manually set in opposition to the restoring force of the torsion spring, this transverse piece is flush with the insertion slot. The reverse rotation of the clamping sleeve produced by the torsion spring causes the slot in the bottom of the clamping sleeve to rotate in relation to the insertion slot in the centering piece so that the transverse piece on the shaft of the jigsaw blade can rest against the bottom of the clamping sleeve and a withdrawal of the saw blade is prevented.